<Title>

Using low sensitivity of direct sequencing to detect K-ras mutations? A new method for improving diagnostic accuracy.

<Author>

Chi-Kuan Chen; Department of Pathology, Mackay Memorial Hospital, Taipei, Taiwan

<Abstract>

Background: Identifying K-ras mutation has became a standard procedure in cancer treatment. Colorectal cancer patients with K-ras mutation are likely to poorly respond to cetuximab. Therefore, detecting K-ras gene mutations should be suggested before the selection of personalized treatment in colorectal cancer. To date, general molecular biology techniques contain HRM, PCR-RFLP, TaqMan PCR and CE-IVD-validated Cobas 4800 KRAS (Roche Diagnostics) are used for K-ras mutation detection in molecular diagnosis, but the sensitivity limitation of these method is approximately 1%.

Methods: Therefore, we used a new approach, a universal genetic detecting method (FemtoPath), which improves sensitivity of K-ras mutation detection and the limitation of sensitivity is closed to 0.1% of mutation type.

Results: We compared the sensitivity between FemtoPath/direct sequencing test and Cobas KRAS real-time PCR. Cobas real-time PCR identifies mutations in 21 (40.38%) of the 52 tumors. Surprisingly, the FemtoPath/direct sequencing test identified mutations in 40 (76.92%) of the 52 tumors. Our data showed that the FemtoPath/direct sequencing test can identify 19 additional mutation samples. In addition, the FemtoPath/direct sequencing test can identify more unknown K-ras mutations adjacent to codon 12 and 13.

Conclusions: Ensure the most timely and appropriate therapy for cancer patients is the first priority of clinical application. FemtoPath/direct sequencing test is more sensitive, accurate and inexpensive and needs fewer sample amount than Cobas real-time PCR.

<link>

http://meetinglibrary.asco.org/content/116160-132